docs: def known(self, words):
          """ The subset of `words` that appear in the dictionary of words
  
              Args:
                  words (list): List of words to determine which are in the \
                  corpus
              Returns:
                  set: The set of those words from the input that are in the \
                  corpus """
          tmp = [w.lower() for w in words]
          return set(
              w
              for w in tmp
              if w in self._word_frequency.dictionary
              or not self._check_if_should_check(w)
          )